"any series of three related works," 1660s, from Greek trilogia "series of three related tragedies performed at Athens at the festival of Dionysus," from tri- "three" (see three) + logos "story" (see logos).

language A strongly typedlogic programming language with numerical constraint-solving over the natural numbers, developed by Paul Voda at UBC in 1988. Trilogy is syntactically a blend of Prolog, Lisp, and Pascal. It contains three types of clauses: predicates (backtracking but no assignable variables), procedures (if-then-else but no backtracking; assignable variables), and subroutines (like procedures, but with input and system calls; callable only from top level or from other subroutines). Development of Trilogy I stopped in 1991. Trilogy II, developed by Paul Voda 1988-92, was a declarative general purpose programming language, used for teaching and to write CL. (http://fmph.uniba.sk/~voda). ["The Constraint Language Trilogy: Semantics and Computations", P. Voda, Complete Logic Systems, 741 Blueridge Ave, North Vancouver BC, V7R 2J5]. (2000-04-08)

a series of three dramas or literary or musical compositions that, although each is in one sense complete, have a close mutual relation and form one theme or develop aspects of one basic concept. The term originally referred specifically to a group of three tragedies written by one author for competition. This trilogy constituted the traditional set of plays presented in Athens by a number of competitors at the 5th-century-BC drama festivals known as the Great Dionysia. One of the first authors to present such a trilogy was Aeschylus, whose Oresteia is the only surviving example from that time. Modern examples of trilogies include Robertson Davies's Deptford Trilogy and Roddy Doyle's Barrytown Trilogy.